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Chemical Equations/Transcript
Transcript Text reads: The Mysteries of Life with Tim & Moby. A man, Tim, and a robot, Moby, are in a laboratory. Moby places a straw into a beaker full of a chemical mixture Tim is holding and starts drinking. (slurping) TIM: Hey! Moby, you should never do that in a lab! You’re going to get me in trouble! Moby hands Tim a letter, which he starts reading. TIM: Dear Tim & Moby, We are doing chemical equations in school next week. What does that mean? From, Wendell. TIM: Well, chemical equations are a way to simply represent chemical reactions. MOBY: Beep? TIM: A chemical reaction is when different substances combine to form a new substance, or when one substance breaks up into different substances. The screen is divided into two equal sections. In one section, an animation shows one white and two red spheres. Each red sphere is connected to the white sphere by a tube. One white and two red spheres break off from the original three spheres but are no longer connected to each other. In the other section, a group of red and white spheres that are not connected is shown. One white and two red spheres separate from the group. Each red sphere is connected to the white sphere by a tube. TIM: When different atoms bond together, new substances are made, with totally different properties than the atoms had on their own. For example, oxygen and hydrogen can combine to form water. An animation shows two clouds. In one cloud there are four moving white spheres, each labeled Upper H. In the other cloud, there are four moving red spheres, each labeled Upper O. The clouds combine and change into a glass of water. TIM: You’ve probably heard water called H2O. That’s its molecular formula. One molecule of water is two hydrogen atoms bonded with one oxygen atom. An image shows one red sphere labeled Upper O and two white spheres labeled Upper H. Each white sphere is connected to the red sphere by a tube. MOBY: Beep? TIM: Well see, every element on the periodic table has its own symbol. An image shows the periodic table. TIM: Symbols usually start with the first letter of the element they represent, like O for oxygen, H for hydrogen, Ar for argon, and Cs for cesium. Using the symbols from the periodic table, we can represent any substance in the universe with a molecular formula. Hydrochloric acid, the stuff in your stomach that digests food, is one hydrogen atom bonded to one chlorine — HCl. A drawing shows the human digestive system. Inside the stomach, a sphere labeled Upper H and a sphere labeled Upper Cl is shown. They are connected by a tube. TIM: The ammonia in this window cleaner is one nitrogen atom combined with three hydrogen atoms — NH3. An animation shows one yellow sphere labeled Upper N and three white spheres, each labeled Upper H. Each white sphere is connected to the yellow sphere by a tube. All of the spheres are subtly rocking back and forth. MOBY: Beep? TIM: We can use those molecular formulas in chemical equations to show how different substances form. For example, table salt is made of one sodium atom and one chlorine atom. An image shows a shaker of salt, a granule of sodium labeled Upper Na, and a cloud of moving spheres, each labeled Upper Cl. TIM: The chemical equation shows the reactants going through a process to form products. The arrow shows what direction the chemical reaction is taking. The granule of sodium and the Upper Cl spheres combine to form a pile of salt. Text reads: Upper Na plus Upper Cl yields Upper Na Upper Cl. MOBY: Beep? TIM: Actually, I sort of lied. It’s not that simple. In reality, chlorine naturally occurs in pairs. An image shows two overlapping brown spheres, each labeled Upper Cl. TIM: So a molecule of chlorine is actually written as Cl 2. Text reads: Upper Na plus Upper Cl 2 yields Upper Na Upper Cl. TIM: You notice anything about that chemical equation? MOBY: Beep? TIM: Well, there’s a chlorine atom missing! See, the reactants have two chlorine atoms and one sodium atom. But the product has only one chlorine atom! An animation shows two overlapping brown spheres, each labeled Upper Cl, connected to one yellow sphere labeled Upper Na. These appear above the reactants Upper Na plus Upper Cl 2. A shaker of salt appears above the product Upper Na Upper Cl. TIM: Since you can’t destroy or create matter, the equation must be wrong. An animation shows a cluster of spheres. It fades out into the background as a “No” symbol flies onto the screen and covers the cluster. Another cluster of spheres fades into the foreground as a “No” symbol flies onto the screen and covers the cluster. TIM: That’s where balancing chemical equations, or stoichiometry, comes into play. To make the equation work, we need to change some of the numbers. You need two sodium atoms to bond with one chlorine molecule. An image shows a yellow sphere labeled Upper Na plus a yellow sphere labeled Upper Na plus two overlapping brown spheres each labeled Upper Cl. Text reads: 2 Upper Na plus Upper Cl 2. An arrow points from this text to the text 2 Upper Na Upper Cl. TIM: They react to form two molecules of salt. The spheres combine to form two piles of salt, each labeled Upper Na Upper Cl. TIM: Now it works. Each side of the equation has two sodiums and two chlorines. This proportion—two sodium atoms for every chlorine molecule—will be the same no matter how much salt you’re making. An image shows two instances of a yellow sphere labeled Upper Na plus a yellow sphere labeled Upper Na plus two overlapping brown spheres each labeled Upper Cl. All of the spheres in both images combine to form four piles of salt. Text reads: 4 Upper Na plus 2 Upper Cl 2 yields 4 Upper Na Upper Cl. An animation shows a yellow sphere labeled Upper Na plus a yellow sphere labeled Upper Na plus two overlapping brown spheres each labeled Upper Cl multiplying 24 times. The spheres then combine to form 63 piles of salt. Text reads: 20,000 Upper Na plus 10,000 Upper Cl 2 yields 20,000 Upper Na Upper Cl. Moby: Beep? TIM: Well, unless you know some pretty high-level algebra, there’s no real method for balancing chemical equations. You just have to use trial and error until the equation balances out. It can take some time. Moby: Beep? TIM: Uh, I don't … I don't know what that is. An animation shows Moby placing a straw into a beaker full of a green liquid and drinking. (slurping) TIM: Cut that out! Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts